The Neuroanatomy Core provides histology, imaging, and stereotaxic surgery services to several of the projects in the P01, as indicated below. Having a core laboratory perform these services, assures the investigators high quality technical help that is overseen by the Core Director, Dr. Elmquist. We have also found that there is also considerable efficiency gained by buying supplies in large lots and by utilizing the talents of a highly skilled technician on a continuing basis for the tasks he has been trained to perform, which further increases his skill levels. As in the previous cycle, the Core does not have Aims per se, but will provide the services to the projects that are necessary for them to achieve a wide variety of scientific aims, including several Aims in this proposal. This includes tissue sectioning, immunohistochemistry, in situ hybridization histochemistry, and assistance in image analysis and production of figures. In addition, the Core will provide assistance with stereotaxic surgical experiments. The establishment of the Core has facilitated the transition of laboratories that do little histology and neuroanatomy (Lowell, Kahn, Flier) from molecular biology and traditional endocrine assays into the field of functional neuroanatomy, as they can take advantage of the technical proficiency of the Core staff and facilities. In addition, investigators who use similar techniques (e.g. Elmquist and Maratos-Flier) can take advantage of economy of scale of isotopes, emulsions, and technician training for specialized procedures.